Background and objective: We sought to evaluate the usefulness of Tc-99m-sestamibi breast scintigraphy in predicting neoadjuvant chemotherapy response in patients with breast cancer.
Patients and method: In 50 consecutive patients with breast cancer stages II and III, physical examination, mammography and scintimammography were performed before and after the administration of neoadjuvant chemotherapy. The 3 assessments were compared for predictive value using a pathological response as reference. Values derived from visual assessment of the scintimammography, a quantitative tumor/background index, and isotope clearance were compared to the immunohistochemical expression of P-glycoprotein, vascular endothelial growth factor (VEGF) and microvessel density (CD31) in relation to neoadjuvant chemotherapy response.
Results: Macroscopic response was obtained in 10 cases (20%). Sensitivity was 86.5% (95% confidence interval [CI], 70.4-94.9) for the physical examination, 83.3% (95% CI, 68-92.5) for the mammography and 76.5% (95% CI, 58.4-88.6) for the scintimammography. Specificity was 38.5% (95% CI, 15.1-67.7) for the physical examination, 42.9% (95% CI, 11.8-79.8) for the mammography and 8.3% (95% CI, 0.4-40.2) for the scintimammography. There were no statistically significant differences in isotope uptake and clearance with regard to response nor in relation to levels of expression of P-glycoprotein, VEGF and microvessel density.
Conclusions: Breast scintigraphy with Tc-99m-sestamibi is not useful in predicting the response to neoadjuvant chemotherapy in breast cancer. Traditional physical examination and mammography are more effective. Isotope uptake and clearance do not predict response and there is not an effective in vivo measurement of chemo-resistance or tumor angiogenesis.